The use of closure fastening devices for the closure of containers, including plastic bag bodies, is generally known. Furthermore, the manufacture of closure fastening devices made of plastic materials is generally known to those skilled in the art relating to closure fastening devices as demonstrated by the numerous patents in this area.
A particularly well-known use for closure fastening devices is in connection with a flexible container, e.g., bag bodies. The closure fastening device and the associated container may be formed from thermoplastic materials, and the closure fastening device and sidewalls of the container can be integrally formed by extrusion as a single piece, or may be formed as separate pieces and then connected by heat sealing or other suitable fastening means.
The closure fastening devices incorporated as closures on bag bodies have been particularly useful in improving the retention of contents in the bag body when the closure is closed. In general, the closure fastening devices on bag bodies have been transparent and the bag body has been made of transparent plastic, thus having the same general appearance for the closure and the bag body. The use of the same transparent plastic for the bag body and the male closure and female closure that form the closure fastening device made it difficult to actually determine when the male and female closures were occluded, i.e., when the bag was closed. Since misalignment of the relatively narrow male and female (typically 90 mils to 120 mils wide) closures could easily occur, there existed a reasonable likelihood that the bag body was at least partially open.
The aforementioned occlusion problem arises from the inability of the user to have a means for identifying when the male and female closure are occluded to form a seal between the contents of the bag and the environment external to the inside of the bag. A solution to this problem is disclosed in U.S. Pat. Nos. 4,186,786, 4,285,105 and Japanese Patent Application No. 51-27719. A color change means for verifying the occlusion of the male and female members of the closure is provided wherein male and female members having different colors are employed and upon occlusion provide a yet different color. For example, the female member of the closure may be opaque yellow and the male member of the closure may be translucent blue. Upon occlusion of the male member and female member a composite color with a green hue results. This use of a color change greatly improves the ability of the user of the interlocking closure device to determine when the male and female members are occluded. Of course, the relative perceivable difference between the colors of the male member, female member and the occluded female/male members is the critical variable that impacts on how well the use of the bag will be able to ascertain when the bag is open or closed.
The change in color that is viewed when dissimilarly colored male and female members are occluded is demonstrated in a commercially available product sold under the trademark GLAD-LOCK (GLAD-LOCK is the registered Trademark of First Brands Corporation, Danbury, CT). The female closure is an opaque yellow and the male closure is a translucent blue. When the male member and female member are occluded, the resulting color has a green hue and provides a color change indicating that the bag body is closed along the length of the closure fastening device. As aforementioned, the ability to ascertain whether the closure device is open or closed is related to the ability of the user to view the change in color of the occluded or unoccluded male and female members of the closure fastening device. Accordingly, any improvement in the relative color change between the male member and female member and the occluded male and female members will provide for improved ease in using the closure device and improved closure devices reliability.
FIGS. 1, 2 and 3 show closures devices that have heretofore been employed as closures on bag bodies. The closure shown in FIG. 1 has been employed as a colored interlocking closure in the manner disclosed in U.S. Pat. Nos. 4,186,786 and 4,285,105. In contrast, the closures shown in FIG. 2 and FIG. 3 have not heretofore been associated with colored interlocking closure devices. Instead, the closures of FIG. 2 and FIG. 3 have heretofore been employed as transparent closure devices having substantially the same transparent coloration as the bag body. As hereinbefore discussed, the use of closures having the same color for the male and female closure elements makes it difficult to visually inspect the closure and reliably detect if the closure is open or closed (occluded). This problem may be particularly troublesome for the closure devices shown in FIGS. 2 and 3 because these closures are relatively small, e.g., less than about 250 mils in width, and, therefore, are not easily grasped for reliable closing. The particular problem associated with aligning and closing small closure elements is discussed in European Patent Application No. 83112946.5. As noted in the European Application, the use of additional ribs on either side of the closure elements has been suggested in the prior art to give an improved "feel" to the closure to provide a stiffer "feel" to the closure and aid in alignment of the closure elements. While the aforementioned European Patent Application addresses an improved manufacturing method for forming the disclosed ribs adjacent the closure element, the problem of visually being able to determine when the closure device is open or closed was not addressed.
The objective in closing an interlocking closure device is best met if the device is both easy to handle (handleability) and easily capable of inspection to determine when the closure device is open or closed. The instant invention is advantageous in that the color change in the color change closure is improved and the instant invention ameiliorates the problem that arises as a result of the presence of additional ribs or guide members on colored interlocking closure devices by including a color change enhancement member in the internal channel of the male and/or female closure members. The presence of a color change enhancement member in the closure channel formed by differently colored male and female members has not been disclosed heretofore for providing improved color change characteristics to color change closure devices. Heretofore, internal elements, e.g., the spring element shown in FIG. 7 of U.S. Pat. No. 4,212,337 as being present in the channel of the male closure element, have not been disclosed to provide any color change function but have been provided solely for sealing. The instant invention relates in one aspect to improved color changes in color closure devices. In another aspect the invention relates to improved color change in wider color closure fastening devices, since it has been observed that in such wider closures (e.g., up to about 250 mils , i.e., wider male and/or female members, closure elements, that there is a decrease in the discernible non-occluded/occluded color change of the translucent male and/or female members as the closure is made wider. Therefore, the instant invention relates to improved color change perception in new closure devices with wider male and/or female closure elements. These wider closures may also have adjacent guide members integrally located adjacent to the male and/or female elements of the closure fastening device. It has been observed that while such "ribs" or "guide members" improve the "feel" of the closure device they may also decrease the discernible color change between the non-occluded and occluded male and female closure elements.